German publication DE-OS No. 2 244 781 discloses an ignition system wherein the closure angle of the switch in series with the ignition coil varies as a function of engine speed. During acceleration, the closure angle changes steadily and, in particular, the speed information during a particular ignition cycle serves to correct the closure angle in the next subsequent cycle. This delay of one cycle in correcting the closure angle can lead to decreased ignition energy when very rapid accelerations occur. This of course is undesirable.